The present invention relates generally to electrical contacts to be connected to conductors and, more particularly, to electrical contacts to be installed in an electrical connector, etc.
Electrical contacts may be divided into two groups; piercing type contacts and crimping type contacts. The piercing type contacts have a piercing portion with a piercing slit into which a conductor is pushed so that the the slit edges pierce the sheath and come to direct contact with the core wire. The crimping type contacts have a pair of gripping tabs to be crimped to the core wire from which the sheath has been removed.
The contact area with the core wire of a piercing type contact is smaller than that of a crimping type contact so that the current carrying capacity of the piercing type contact is smaller than that of the crimping type contact. However, the piercing type contacts are inexpensive because of their simple piercing operation and are widely used for electronic equipment which has a large number of circuits or signal lines carrying little current. By contrast, the crimping type contacts are commonly used for power lines because of their large current capacity.
Since the piercing and crimping type contacts have completely different structures, there have arisen the following problems:
(1) Recent electronic equipment requires high density mounting in which it is desired to mount both signal and power lines in the same connector. However, since the piercing and crimping type contacts are completely different in structure, many types of contacts and in turn connectors with different apertures receiving the different contacts must be provided. This increases the manufacturing costs of contacts and connectors and makes their management more difficult.
(2) Since both signal and power lines cannot be mounted in the same contact, it is difficult to achive high density mounting.
(3) When a signal line already mounted is to be exchanged with a power line or vice versa, the whole connector must be changed to another type, not only requiring additional work and additional cost but also making the circuit maintenance difficult.
(4) Individual contacts must be selected by observation according to customer's contact combination requirements, and the selected contacts must be connected to the corresponding conductors by hand. The connected contacts are assembled in a connector housing by hand, thus requiring large amounts of work and cost.
Piercing type electrical contacts are well known. For example, Japanese Patent Kokai No. 60-130,571 discloses a piercing type contact which has on the front side a female contacting section for receiving a male contact and on the rear side a pair of piercing walls with a piercing slit which penetrates the sheath and comes into direct contact with the core wire. The piercing walls are disposed in spaced parallel planes perpendicular to the axis of the conductor and each have a slit of the same width. When a conductor is pushed into these slits, the slit edges penetrate the sheath, not only coming into direct contact with the core wire but also holding the conductor in place.
In the above contacts, the thickness of a connectable conductor by piercing is determined by the slit width. Consequently, a conductor of a different thickness is to be connected, a different contact is required. Thus, various types of contacts must be made, resulting in the increased manufacturing cost. In addition, the difference in slit width between various contacts is so small that it is difficult to select right ones with naked eye, which can cause wrong contact selection, resulting in a poor connection between the contact and the conductor.